Alternator expert needed [Archive] - Forum


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10-12-2011, 05:08 PM
Alright so i have a sound system in my car and it was too much so it was dimming lights. I bought a 220 amp alternator online. It was supposed to be a direct replacement but my alternator has a 4x1 connector that is labeled P L F S and it only uses the L & S ports. The other two are filled with rubber plugs. The new alternator had only a 2x1 connector with wires labeled L & F so i cut and spliced the the new connector onto my wires but the connection then was L to L and S to F.

Anyways, It worked great for 2 weeks, no dimming or other problems. Then i went to the grocery store, came out, started the car and i only made it a few feet before everything started to shut off. I got a jump, and it drove fine for 20 minutes until i got home. The next morning it wouldn't start so i jumped it assuming my battery just wouldn't hold a charge, but once my car was running it wouldn't stay running for more than a minute or so depending on the charge of the battery. I put the original working alternator back on this morning and it is still dying after a minute or two.

Did i mess something up by connecting those two wires? Should i have only connected the L wires and left the other ends loose? What do these wires go to? and lastly, any ideas on how to fix this issue?

Thanks for your time,

10-12-2011, 05:44 PM
Maybe my 2003 GAGT charging schematic ( 43138) might help you.

10-13-2011, 03:20 PM
Should have sent it back as soon as you saw the plug wasn't right. There are actual high output alternators out there that really do fit with no modification. Anyway... I'd get a capacitor (or two, depending on your amps) for the system before getting a bigger alternator. Batteries and alternators have higher resistance and slower reaction speeds to load changes than capacitors do, and they aren't made to respond to the kinds of demands high power amps put on them. Simply adding a good quality cap can usually solve your power demand problems and help your battery and alt last longer too.

Anyway, it's possible you might have hooked the wires up wrong and fried something in the PCM or fuse block. It's also possible that just from the higher load you might have burned up the fusible link and it's intermittently getting connected and disconnect, causing the car to lose power and shut off. The main charging wire from the alt goes down to the starter motor first, then from there to the battery and the under hood fuse block. The bluish wire connected to the starter solenoid is the fusible link (it's printed on the insulation too). Might have to pull back some tape and wire loom, but take a look at that and see if it looks discolored, melted, or unusually stiff. Might have to replace it, or just run another wire. That is another upgrade that many people do, and should also be considered before upgrading the alternator. The stock power wire is rather small and causes voltage drop. Try running a larger gauge wire (like 4-6 awg) from the alternator post directly to the positive battery post. You can also do that to the fuse block and starter if you want. I did with mine. That will let the current alternators full voltage get to the system.

10-13-2011, 04:29 PM
um a 220 wont produce enough power at idle. it just wont happen in that size of case. could also be the reason for dead batts. jus sayin.

20 min on highway or city?

10-13-2011, 06:37 PM
Thanks guys, turns out i'm just an idiot and in the rush to try to get it to run before work i forgot to plug the harness into the the stock alternator when i put it back on, so the car runs correctly, 14.5 vdc at the battery, drove it to work no problem. So maybe having the wrong plug ruined the other alternator?

I'm exchanging emails with a tech from the place that shipped it to me, he can't believe it isn't the right plug so i have to get him a picture.